The idea of a complete community is one where everyone can access the places of their interest within a reasonable amount of time and travel there however they prefer. We have built on a methodology to be able to score different communities in order to compare relatively how complete they are.

At a very high level, the methodology involves analyzing how long it takes to travel to various amenities for each resident. Various simplifications are indeed required to make this feasible however.

One such simplification we made is that residents were spatially aggregated into Census blocks. This is illustrated in the above maps of San Ramon and Antioch, the cities we will be applying our methodology to. This will still lead us to having enough granularity to see the geographic variation of completeness in a city, and this improves upon the original methodology that used the larger block groups. The centroid of these blocks will be used as the origins of the trips to the various amenities in our analysis.

Another simplification we made is that we chose some specific places of interests to represent the amenities people value. We chose to analyze 12 amenities, more than doubling the amount from the original methodology. Notably, we included many more medical related places such as hospitals, pharmacies, medical practices, and dentists’ practices as we wanted to better encapsulate a community’s concern for their health. This is in addition to the recreational amenities we included such as parks, swimming pools, and sports centers which we used as a way to represent a community’s interests in leisure as well as other important locations of a community such as supermarkets, convenience stores, restaurants, schools, and libraries where community members may go to fulfill important basic needs.

The methodology then includes producing isochrones (boundaries of how far one can travel in a given amount of time) from the centroid of each block. We then used subjective weights to map value to each amenity. For the reduction in value for each additional amenity of a POI type, we used the same methodology of modeling the decay with an exponential function. For the reduction in value for a trip the longer it takes, we instead used a reversed sigmoid function. We did this because we felt that people are more likely to categorize locations as roughly near or far in their mind and the biggest value drop occurs between those categories (occuring at the reasonable time point).

This relationship is illustrated in the graph above for the decay in value of a trip with a reasonable time of 20 miutes. One can see that the main difference between this method and the original exponential function method is that times before the reasonable time for the trip are given a higher value.

Now we will now compare completeness across two different cities, namely Antioch and San Ramon.

It is the cities’ stark differences that motivated our selection of them. Although both cities are located in Contra Costa county, Census data reveals that, in the past five years, the median household income of Antioch was around half of San Ramon’s (77,000 USD to 161,000 USD). However, this drastic income difference does not appear to correspond to a drastic difference in community completeness. Antioch has only a slightly worse completeness score than San Ramon (1.03 compared to 1.10). Notably there is a larger difference in the driving completeness scores (1.94 to 2.04) than the walking scores (0.15 to 0.16) implying that the completeness score difference is at least partially due to San Ramon having a better road infrastructure. This is highlighted in the map above where locations near the main highway in San Ramon appear to have a higher completeness score.

The chart above shows the sorted completeness scores per census block, visualizing the distribution of completeness scores for each city. The most significant difference is that Antioch has many more blocks at the lower end of the spectrum and Ramon has some more blocks at the upper end of the spectrum. It is also interesting that the overall shape of the curves appear to be similar, showing that the cities share a similar shape in the distribution of completeness scores.

We will also look at how this completeness is distributed among residents of each city to see if the scored accessibility is distributed equitably. We performed this equity analysis by comparing how racial distribution of the full population of each city to the racial distribution of those within a 5 minute drive of a hospital. This specific trip was picked as proximity to a hospital can be the difference of life and death.

We can see large differences in both cities. In San Ramon, Asians are much less likely to have access to hospitals compared to blacks. This may indicate that the few black communities in San Ramon are centered near hospitals while Asians may be living in father, more affluent areas, but more research would be needed to certify such conclusions

In Antioch, there is not as big of a difference between both charts, but it does appear that whites are more likely to live near a hospital as opposed to blacks.

Overall, it does appear that Antioch has a more equitable distribution. It is noteworthy that this may be associated with how Antioch is a more diverse city than San Ramon as whole as well as the previously mentioned differences in income of the cities’ residents. Additionally, while this is indeed only analyzing the proximity of one amenity, not only may it be representative of the equitability of the completeness of the cities as a whole, but hospitals are, as previously mentioned, a vital amenity. A lack of proximity of hospitals can lead to unnecessary deaths, thus conveying how impactful inequity may be.

This estimate of a community’s completeness tries to capture how accessible a city’s places of interests are to its members. Unfortunately, there are many aspects of how accessibility and the lack thereof are not captured with this methodology with one prime example being the spatial aggregation of completeness scores when accessibility inherently differs from person to person as corresponding to their distinct needs and desires. However, this methodology is still useful for a city to approach being more accessible. The methodology is quite useful in producing a specific metric with enough granularity so that city planners can know where to focus on where to improve. The metric is also a very direct way of measuring accessibility and thus a city’s incentive to increase one’s completeness score would be tied with actually increasing accessibility for their residents. Therefore, this estimate of a community’s completeness is a solid step in the right direction in seeing how to improve the accessibility of a community.